Core feeding method in a rewinding machine for making logs of sheet material

ABSTRACT

A rewinding method for a web ( 1 ) of sheet material for making a log ( 2   a ) wound on a core ( 20   a,   20   b,   20   c ) in a winding zone ( 4 ) formed between an upper winding roller ( 5 ) and a lower winding roller ( 6 ), in particular for the production of rolls of toilet paper, rolls of all purpose tissue paper or non woven fabric for household use, industrial rolls and the like. Upstream of the winding zone ( 4 ) a cradle ( 21,26 ) is provided for feeding the core ( 20   b ) connected to the support ( 29 ) of the lower roller and located beneath the upper winding roller ( 5 ). At least a portion ( 21 ) of the cradle ( 21,26 ) is movable with respect to the support ( 29 ) of the lower roller ( 5 ) and is capable of lowering or rising towards/away from the upper winding roller ( 5 ). For each step of feeding a core ( 20   b ), the movable portion ( 21 ) can be displaced from a first position of load of the core ( 20   b ) to a second position wherein the core ( 20   b ) contacts the upper roller ( 5 ). When the upper roller ( 5 ) contacts the core ( 20   b ) for reaching the winding zone ( 4 ) it moves first on the movable portion ( 21 ) and then on a fixed portion ( 26 ) of the cradle that is integral to the support ( 29 ) wherein the axle rotates of the lower roller ( 5 ).

FIELD OF THE INVENTION

[0001] The present invention relates to a core feeding method in arewinding machine for making logs of sheet or web material, for exampleused for the production of rolls of toilet paper, rolls of all purposetissue paper for household use, non woven fabric, industrial rolls andthe like.

[0002] Furthermore the invention relates to a rewinding machine thatcarries out this method.

DESCRIPTION OF THE PRIOR ART

[0003] Rewinding machines are known wherein a log is wound that is incontact surface with winding rollers. More precisely, the log is formedstarting from a web of paper, continuous or with transversalperforations, which, carried by a first conveyor, is wound partially onan upper winding roller, enters into contact with a lower winding rollerand is kept against the two upper and lower winding rollers by apressure roller. The three rollers define a winding zone wherein the logis formed by feeding the web of paper and by dragging it for surfacecontact.

[0004] Normally, in the winding zone the log is formed on a tubularcore. Once the log has reached a predetermined diameter, with a controlnormally on the paper length as wound, the web is cut or torn and thelog is pushed away from the winding zone at the side opposite to theintroduction zone of the core and, at the same time, a core is put in bya pusher.

[0005] Some rewinding machines, at the end of each winding step, providea blade that cuts transversally the web against the upper windingroller, which has one or more cutting slots with which a retractableblade engages mounted on an adjacent cutting roller.

[0006] In the case, instead, of rewinding machines with tearing system,the web is stopped upstream of or on the upper winding roller and thetearing is caused by the dragging action on the stopped web of the lowerwinding roller, on which the log is pushed by the pressure roller.Normally, a speed difference is created between said two rollers at thechange of the log for causing the tearing.

[0007] Many methods exist for feeding the core into the winding zone. Ina first case, a core at a time is fed on a loading tray and a pusherputs it into a winding zone. In this case, the pusher forces in aconcentrated way against the core for forcing it between the windingrollers in presence of the paper, and it can get dented in the zone ofcontact, producing a faulty winding.

[0008] In a second case, the core is brought on a feeding cradle ofcurved shape located under the upper winding roller, whereby thefriction against the upper roller brings it forward up to the contactwith the lower winding roller for starting the winding. The cradle isformed by a series of curved guides that protrude rearwardly from thelower winding roller and are to it completely integral.

[0009] In presence of the feeding cradle, there is the advantage that apad can be inserted between the core feeding point and the winding zonefor tearing the paper. This way, the torn portion that is locatedupstream is caught automatically by the incoming core that is dragged bythe upper roller against the cradle located underneath.

[0010] According to the size of the core, the lower roller is broughtforward or away from the upper roller. However, a different cradle isnecessary for each different diameter of the core. This causes stops inthe production, an adjusting work and the need of a set of cradles, onefor each different diameter of the core.

SUMMARY OF THE INVENTION

[0011] It is an object of the present invention to provide a rewindingmethod for a web of paper for making logs, wherein the introduction ofthe core is carried out automatically on a cradle located beneath theupper winding roller, but wherein the change of the feeding cradle isnot necessary according to the different diameter of the core.

[0012] It is another object of the present invention to provide arewinding machine of a web of paper for making logs that is capable ofcarrying out this method.

[0013] These and other objects are reached by the winding method of aweb for making a log whose characteristic is that it comprises the stepsof:

[0014] feeding a web of paper in a winding zone formed between an upperwinding roller and a lower winding roller;

[0015] arranging upstream of the winding zone a core feeding cradleconnected to the lower roller, the cradle being located beneath theupper winding roller and extending from a core feeding zone up to thelower winding roller;

[0016] Its characteristic being that at least a portion of the cradle ismovable with respect to the support of the lower roller and is capableof lowering or rising towards/away from the upper winding roller.

[0017] Preferably, for each feeding step of a core, the movable portionof the cradle can be displaced from a first position of load of the coreto a second position wherein the core contacts the upper roller.

[0018] In its movement of lowering/rising, the cradle can rotate about apivot concentric to the lower roller.

[0019] Advantageously, for reaching the winding zone and remaining incontact with the upper roller, the core moves on the movable portion ofthe cradle and then on a portion of the cradle that is integral to thelower roller. Furthermore for reaching the winding zone remaining incontact with the upper roller, the core is pushed by the cradle againstthe upper roller in a resilient way.

[0020] Preferably, the core is put on the cradle when the movableportion is in lowered position, rolling on a downhill portion of themovable portion up to reaching a peeping stop element.

[0021] In particular, the steps can be provided of:

[0022] rising the core by means of the movable portion up to anapproached position to the upper roller without that there is contactwith the latter,

[0023] starting from the approached position further brief risingmovement of the core until it is pushed against the upper windingroller, whereby the latter can bring it forward towards the windingzone.

[0024] If the web is not cut or torn upstream, the contact of the coresame against the upper winding roller causes the tearing of the webalong a line of transversal perforation that is located between the coreand the winding zone. In this case a step is provided of stretching theweb between the core and the winding zone.

[0025] According to another aspect of the invention, a rewinding machineof a web for making a wound log on a core, in particular for theproduction of rolls of toilet paper, rolls of all purpose tissue paperor non woven fabric for household use, industrial rolls and the like,comprises:

[0026] means for feeding and dragging a web of paper;

[0027] a winding zone where a log is wound downstream of the means forfeeding the web;

[0028] means for feeding the core;

[0029] a core feeding cradle arranged upstream of the winding zone, thecradle being located beneath the upper winding roller and extendingbetween the means for feeding the core up to the lower winding roller;

[0030] Its characteristic being furthermore that it comprises means forlowering/rising the cradle with respect to the lower roller towards/awayfrom the upper roller.

[0031] Preferably, the cradle has a resilient surface for adapting tothe passage of the core pushing it against the upper roller. Inparticular, the cradle has a curved surface with concavity orientedtowards the upper roller.

[0032] Advantageously, the means for lowering/rising the cradletowards/away from the upper winding roller are operatively connected toan arm pivoted to the same support wherein the axle of the lower windingroller rotates.

[0033] Preferably, the cradle has a fixed portion integral to the lowerroller located downstream of the movable portion, the movable portioncooperating with the fixed portion in order to form a single surface ofsupport for the core during winding. Starting from the edge of the meansfor feeding the movable portion may have a portion downhill and apeeping stop element.

[0034] Means are provided for controlling the means for lowering/risingselectively the movable cradle to a predetermined height with respect tothe upper winding roller.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Further characteristics and/or advantages of the rewinding methodand of the rewinding apparatus according to the present invention willbe made clearer with the following description of an embodiment thereof,exemplifying but not limitative, with reference to attached drawingswherein:

[0036]FIG. 1 shows a cross sectional view of a rewinding machineaccording to the present invention;

[0037] FIGS. from 2 to 5 show four different positions of the tail ofthe web of the wound log and of the head of the web of the log to bewound, as well as the steps of feeding the log in the core.

DESCRIPTION OF A PREFERRED EMBODIMENT

[0038] With reference to FIG. 1, a rewinding machine of a web 1 formaking a log 2 a comprises a roller 3 for feeding web 1 and, downstreamof it, a winding zone 4 where the log 2 a same is wound.

[0039] Winding zone 4, according to the prior art, is formed by an upperwinding roller 5, a lower winding roller 6 and a pressure roller 7. Thelatter follows the growth of the log 2 a with the task of assuring itscontinuous contact with the winding rollers 5 and 6 and of controllingthe growth of its diameter.

[0040] Between feeding roller 3 and upper winding roller 5 a countersupport roller 8 is provided on which web 1 rests. Counter supportroller 8 can be driven independently and comprise cutting means 10 thatengage with a cutting slit 9. Alternatively, the cutting roller canoperate directly on upper roller 5.

[0041] At the end of each log, blade 10 engages with countersupportroller 8 (or with upper roller 5) for cutting web 1, thus creating atail end 1 a of the previous log 2 a and a head end 1 b of a log to beformed.

[0042] The log 2 a already wound continues to be brought into rotationin zone 4 for tangential friction against upper winding roller 5, lowerwinding roller 6 and pressure roller 7.

[0043] The winding was started by a core 20 a, which had been put intozone 4 by a chain conveyor 22. Furthermore a core 20 b is ready forbeing a winding support for a log to be wound starting from the headportion 1 b of web 1.

[0044] According to the invention, upstream of zone 4 a cradle isprovided 21,26 for feeding a core 20 b. Cradle 21,26 is located beneathupper winding roller 5 and extends between the chain conveyor 22 of thecore up to lower winding roller 6. Cradle portion 21 is movable and iscapable of lowering or rising towards/away from upper winding roller 5.At the end of movable portion 21, core 20 b is brought by a fixedportion 26, to which the terminal portion 21 a of movable portion 21 isadjacent.

[0045] More precisely, in its movement of lowering/rising movableportion 21 rotates integrally to an arm 23 pivoted concentrically tolower roller 6. A driven shaft 24 by means of a lever 25 is capable ofoperating the movement of lowering/rising arm 23 and then cradle 21.

[0046] Always with reference to FIG. 1, core 20 b is put on movableportion 21 when it is in a lowered position, rolling on a downhillstarting portion 21 b up to a peeping stop 27. Then, as shown in FIG. 2,core 20 b approaches upper roller 5 without contacting it.

[0047] Then, at the end of winding the previous log 2 a, when the lineof cutting/tearing 31 is located between core 2 b and winding zone 4,with short and quick rising movement (FIG. 3) core 20 b is brought bycradle 21 into contact with upper winding roller 5 that brings itquickly forward (FIG. 4), beyond peeping stop element 27 and towardslower winding roller 6.

[0048] Peeping stop element 27 can be a harmonic steel blade, as thatshown in the figure, or it can be a finger hinged to movable portion 21and yielding by means of the action of a spring at the passage of thecore (FIG. 3).

[0049] According to the prior art, core 20 b is preglued along at leasta line, whereby it quickly catches end 1 b at the passage from thepositions of FIGS. 3 and 4, moving on movable portion 21.

[0050] Both movable portion 21 and fixed portion 26 have a curvedsurface with concavity oriented towards the upper roller. This surface,in a way not shown, may be resilient. For example it may have a surfacecoated of spongy material, or a plate suspended on springs, or a surfaceformed by a belt stretched between two ends.

[0051] As shown in FIG. 5, core 20 b reaches the winding zone 4previously abandoned by log 2 a. A log 2 b starts to be wound forrotation of rollers 5, 6 and 7, as indicated by the relative arrows. Acore 20 c is put in by chain conveyor 22 after that the movable portion21 of the cradle, integrally to arm 23, has been lowered by connectingrod 25 by means of driven shaft 24. The new core 20 c rolls on the shortdownhill portion 21 b and reaches peeping stop element 27.

[0052] If the new core has not the same diameter as the previous one, itis necessary to adjust the machine for a new production campaign. Moreprecisely, according to the different diameter of the core, lower roller6, according to the prior art, is displaced in the direction of arrow28, substantially in direction towards/away from the centre of lowerroller 5. In this case, both fixed portion 26 and movable portion 21,along with arm 23, follow integrally lower roller 6.

[0053] It is not, however, necessary to replace the cradle formed byportions 21 and 26, since they have curved shape and movable portion 21is rotatable about support 29, in which the axle of lower roller 6rotates, whereby when it presses onto core 20 b (FIGS. 3 and 4) itassures in any case the presence of a rolling channel for the core, thusassuring that the core does not lose the contact with upper roller 5 orthat it is too much squeezed. This aspect is particularly advantageouswith respect to the machines that at the change of diameter of the corehave fixed cradles necessarily changed.

[0054] As above said, the winding steps of web 1 for making a log 2 acan provide the cut of the paper upstream of upper winding roller 5(FIG. 1). In this case, the web of paper 1 is fed in the winding zone 4about core 20 a up to a predetermined development upstream of thefeeding roller 3. Then, once the chosen length of web 1 upstream of zone4 has been unwound, countersupport roller 8 at cutting slot 9 withtransversal blade of cutting roller 10 cut or tear web 1 separating thetail end 1 a from head end 1 b. From this moment the various steps arethen successively carried out of bringing head end 1 b towards thewinding zone, not described in detail, but shown in EP1016608.

[0055] Alternatively, the contact of core 20 b same against upperwinding roller 5 can cause the tearing of the paper 1 along a line oftransversal perforation 31 of the paper that is located between core 20b and winding zone 4. In this case a step is provided of stretching theweb between the core and the winding zone. This stretching can becarried out by accelerating the abandonment movement of already woundlog 2 a, for example, according to the prior art, with interpositionbetween already wound log 2 a and the lower roller of a fixed tray 32(FIGS. 3,4,5), whereby log 2 a runs quickly away on tray 32.Alternatively, always in a known way, the tearing step is carried out byacceleration of pressure roller 7 with respect to lower roller 6.

[0056] The preferred embodiment of the invention of FIGS. 1-5 has beenshown only through a cross sectional view in five operative positionsand not with a top plan view or an elevational view, that are notnecessary since obvious for a man of the art. In such top plan orelevational views rollers 3, 8, 10, 5, 6 and 7 and driven shaft 24 wouldbe seen that extend for all the maximum length of log 2 a and of core 20a, with ends that engage with support walls by means of bearings as wellas drive and transmission elements. Cradle 21,26 would be seen as aplurality of arms 23,26 arranged some centimeters from one another andconnected to support 29 wherein the axle rotates of lower roller 6.

[0057] The foregoing description of a specific embodiment will so fullyreveal the invention according to the conceptual point of view, so thatothers, by applying current knowledge, will be able to modify and/oradapt for various applications such an embodiment without furtherresearch and without parting from the invention, and it is therefore tobe understood that such adaptations and modifications will have to beconsidered as equivalent to the specific embodiment. The means and thematerials to realise the different functions described herein could havea different nature without, for this reason, departing from the field ofthe invention. It is to be understood that the phraseology orterminology employed herein is for the purpose of description and not oflimitation.

1. Rewinding method for a web (1) of sheet material for making a log (2a) wound on a core (20 a,20 b,20 c), in particular for the production ofrolls of toilet paper, rolls of all purpose tissue paper or non wovenfabric for household use, industrial rolls and the like, comprising thesteps of: feeding a web of paper (1) in a winding zone (4) formedbetween an upper winding roller (5) and a lower winding roller (6);arranging upstream of the winding zone (4) a cradle (21,26) for feedingthe core (20 b) connected to said lower roller, said cradle (21,26)being located beneath the upper winding roller (5) and extending from acore feeding zone (20 b) up to said lower winding roller (6);characterised in that at least a portion (21) of said cradle (21,26) ismovable with respect to the support (29) of said lower roller (5) and iscapable of lowering or rising towards/away from said upper windingroller (5).
 2. Method according to claim 1, wherein, for each step offeeding a core (20 b), said at least one portion (21) of said cradlethat is movable with respect to the support (29) of said lower roller(6) can be displaced from a first position of load of said core (20 b)to a second position wherein said core (20 b) contacts said upper roller(5).
 3. Method according to claim 1, wherein in its movement oflowering/rising (24,25) the movable portion (21) rotates (23) about apivot (29) concentric to said lower roller (5).
 4. Method according toclaim 1, wherein said core (20 b) for reaching said winding zone (4)even if remaining in contact with said upper roller (5) moves first onsaid at least one movable portion (21) and then on a fixed portion (26)of said cradle that is integral to the support (29) wherein the axlerotates of said lower roller (5).
 5. Method according to claim 1,wherein said core (20 b) for reaching said winding zone (4) even ifremaining in contact with said upper roller (5) is pushed by said cradle(21,26) against said upper roller (5) in a resilient way.
 6. Methodaccording to claim 1, wherein said core (20 b) is put on said cradlewhen said movable portion (21) is in lowered position, rolling on adownhill portion (21 b) of said movable portion up to reaching a peepingstop element (27).
 7. Method according to claim 1, wherein the steps areprovided of: rising (24,25) of said core (20 b) by means of said movableportion (21) up to a position approached to the upper roller (5) withoutthat there is contact with the latter, starting from said approachedposition, further short rising movement (24,25) of said core (20 b) upto be pushed against said upper winding roller (5), whereby the lattercan bring it forward towards the winding zone (4)
 8. Method according toclaim 1, wherein the contact of the core (20 a,20 b,20 c) same againstthe upper winding roller (5) allows the tearing of the web (1) along aline of transversal perforation (31) that is located between the core(20 b) and said winding zone (4), a step being provided of stretchingthe web (1) between said core (20 b) and said winding zone.
 9. Arewinding machine of a web (1) for making a log (2 a) wound on a core(20 a,20 b,20 c), in particular for the production of rolls of toiletpaper, rolls of all purpose tissue paper or non woven fabric forhousehold use, industrial rolls and the like, comprising: means forfeeding and dragging (3,8) a web (1) of paper; a winding zone (4) wherea log is wound (2 a) downstream of the means for feeding (3,8) the web(1); means for feeding (22) the core (20); a cradle (21,26) for feedingthe core (20 b) arranged upstream of the winding zone (4), said cradle(21) being located beneath the upper winding roller (5) and extendingbetween said means for feeding (22) of the core (20) up to said lowerwinding roller (6); characterized in that it comprises means forlowering/rising (23,24,25) at least one movable portion (21) of saidcradle (21,26) with respect to said lower roller (6) towards/away fromsaid upper roller (5).
 10. Apparatus according to claim 9, wherein saidcradle (21,26) has a resilient surface for adapting to the passage ofsaid core (20 b) when pushing it against said upper roller (5). 11.Apparatus according to claim 9, wherein said cradle (21,26) has a curvedsurface with concavity oriented towards said upper roller (5). 12.Apparatus according to claim 9, wherein said means for lowering/rising(24,25) said cradle (21) towards/away from said upper winding roller (5)are operatively connected to an arm (23) pivoted to the support (29)wherein the axle rotates of said lower winding roller (6).
 13. Apparatusaccording to claim 9, wherein said cradle has fixed portion (26)integral to the support (29) wherein the axle rotates of said lowerroller (5) at the end of said movable portion (21), said movable portion(21) cooperating with said fixed portion (26) in order to form a singlesurface of support for core (20 b).
 14. Apparatus according to claim 9,wherein starting from the edge of said means for feeding said movableportion (21) has a downhill portion (21 b) and a peeping stop element(27).